Die forging machine



Dec. 5, 1967 Filed May 25, 1965 2 Sheets-Sheet 1 FIG luv'em'o BRUNO KHAW-OM51;

Dec. 5, 1967 B. KRALOWETZ 3,355,931

DIE FORGING MACHINE Filed May 25, 1965- 2 Sheets-Sheet 2 United StatesPatent 3,355,931 DIE FORGING MACHINE Bruno Kralowetz, Weinleiten 142,St. Ulrich, near Steyr, Austria Filed May 25, 1965, Ser. No. 458,661Claims priority, application Austria, July 10, 1964, A 5,945/ 64 2Claims. (Cl. 72-404) ABSTRACT OF THE DISCLOSURE A die forging machinehaving one pair of mutually opposed hammers provided with preshapingtools, and another pair of mutually opposed hammers provided withfinishing dies. The two pairs of hammers are disposed in a common planeand spaced apart by 90 angles. Compressed gas drives the two pairs ofhammers alternately against opposite sides of bar stock introducedbetween the hammers.

This invention relates to a die forging machine, in which die-carryinghammers blow from opposite sides against the bar stock which isintroduced between the dies. A known machine of this type comprises twohammers, which constitute connecting rods driven by eccentrics. Eachhammer carries a preforging die and a finishing die one beside theother. A feeding mechanism consisting of a plurality of displaceablegrippers, which grip in alternation, is provided for an intermittentfeeding of the workpiece. The entire deformation of each workpieceportion is effected by a plurality of hammer blows. As the number ofblows per unit of time cannot be indefinitely increased with sucheccentric-driven hammers, for design reasons, deforming speeds in excessof 0.3-0.4 meter per second cannot be used. It is impossible or verydifiicult to forge various workpieces or workpieces of differentmaterials at these relatively low speeds. It is also undesirable toarrange the preforging and finishing dies one beside the other becausethis gives rise to forging forces which are eccentric with respect tothe hammer axis, which coincides with the main axis of the machine.These forces cannot be controlled with economical means at relativelyhigh blowing speeds. Besides, the arrangement of one die beside theother requires larger and heavier hammers.

It is also known to drive hammers by compressed gas and to return thehammer by applying hydraulic pressure from the opposite end, whilecompressing the gas, so that a mechanical drive for the hammers iseliminated. This results in very high blowing and shaping rates. Thishammer drive, however, has not been applied before to the continuousmanufacture of die forgings from bar stock but has only been applied toforging processes involving a great deal of manual work on the machine.

It is an object of the invention to eliminate these disadvantages andprovide a die forging machine which enables a manufacture of workpieceseven from diflicultly deformable material in a continuous, highlyautomatic operation with a long die life and a good shaping to thedesired form.

The invention resides essentially in that a pair of hammers providedwith finishing dies, and another pair of hammers, which are offset by anangle of 90 from the former and whose axis lies in the same normal planeto the workpiece aXis, are provided, said other pair of hammers carryingpreshaping dies or preshaping tools, the two pairs of hammers blow inalternation and at least the pair of hammers which carries the finishingdies is adapted to be driven by compressed gas in known manner. Thedrive by means of compressed gas permits an increase in blowing speed to15 meters per second and more and ensures that the workpiece is finishedby one blow and at high speed and with a short contact time between thetool and the workpiece. This so-called high-energy shaping results in animproved die life and a better filling of the die, and it has been shownthat even workpieces which cannot be shaped or can be shaped only withdifliculty at lower shaping speeds can now be manufactured with good orvery good success. Materials which cannot be forged at normal blowingspeeds exhibit different properties at higher forging speeds. To ensurea favorable distribution of material in the finishing die, almost anyworkpiece must be preshaped. In many cases, this preshaping may resideonly in bending or stretching. The additional pair of hammers isprovided for preshaping. Due to the provision of a separate pair ofhammers, the previously occurring, eccentric stresses on the hammers,the hammer guides and the machine frame are avoided. Such stresses wouldbe intolerable during shaping operations at high speed. Besides, eachhammer can be designed with small dimensions and with a light weight asit must carry only one die or tool so that it can be accelerated to avery high velocity by a desired, predetermined blowing energy. Thepreshaping may be effected in a plurality of blows. During thepreshaping, the workpiece may be rotated and may also be displaced inits longitudinal direction. In many cases it will be necessary to rotatethe workpiece through when it has been preshaped so that the workpieceis in its correct position relative to the finishing dies. Thearrangement according to the invention is particularly desirable forforging cranked portions because in this case the finishing dies can beapplied immediately after the workpiece has been prebent or offset bythe preshaping tools without need for rotating the workpiece.

An embodiment of the invention is: shown by way of example on theaccompanying drawings, in which FIGS. 1 and 2 show a die forging machinein a sectional view taken transversely to the workpiece axis and in asectional view taken along this axis. For the sake of clearness, thefeeding mechanism and other details are not shown.

A forging box 1 forms guides 2 for four hammers 3, 4, which areangularly spaced 90 apart and whose axes lie in the same vertical plane.The hammers 3, 4 are connected by rods 5 to pistons 6, which areslidable in cylinders 7. The blowing movements of the hammers 3 and 4are directed toward each other and effected by compressed gas, whichdoes not act directly on the pistons 6, but operates an auxiliarypiston, not shown, from which the movement is hydraulically transmittedby the supply conduits 8 to the pistons 6. The return of the pistons 6to their initial position and of the hammers 3, 4 to their position ofrest is effected by the application of pressure liquid to the rod endsof the pistons 6 through the conduits 9. During the blowing movement,the pressure fluid is displaced from this end of the piston into apressure accumulator 10 associated with each piston.

The two hammers 3 carry pre-shaping dies 11 and the hammers 4 areprovided with the finishing dies 12. When the bar stock has been heated,it is moved between the pairs of hammers 3, 4 by a feeding mechanism,which is not shown. While the hammers 4 are retracted, the bar end isthen preforged by means of the hammers 3 and the preshaping tools 11.The workpiece may then be rotated through 90 and is subsequentlyfinished by a single blow of the hammers 4 and the finishing dies 12. Atemperature measuring instrument (not shown) checks each workpiece forthe correct forging temperature and by means of an electric controlcircuit initiates the automatic forging cycle only when the forgingtemperatures are within the desired, adjustable range. When the firstworkpiece has been finished, the bar is advanced to a suitable extentand the entire cycle is repeated.

What I claim is:

1. A die forging machine, which comprises a first pair of mutuallyopposite hammers, each of which carries a pre-shaping tool, a secondpair of mutually opposite hammers, each of which carries a finishingdie, said pairs of hammers being disposed in a common plane and spacedfrom each other by an angle of 90, and hammer drive means for drivingsaid pairs of hammers in alternation to perform blows against oppositesides of bar stock introduced between said hammers in a longitudinaldirection which is normal to said plane, said hammer drive meanscomprising a compressed gas source for driving said second pair ofhammers.

2. A die forging machine, which comprises a first pair of mutuallyopposite hammers, each of which carries a pre-shaping tool, a secondpair of mutually opposite hammers, each of which carries a finishingdie, said pairs of hammers being disposed in a common plane and spacedReferences Cited UNITED STATES PATENTS 330,262 11/1885 Richardson72-404- 443,030 12/1890 Wood 72-402 455,905 7/1891 Thomson 724033,263,465 8/1966 Way 72-294 CHARLES W. LANHAM, Primary Examiner.

G. P. CROSBY, Assistant Examiner.

1. A DIE FORGING MACHINE, WHICH COMPRISES A FIRST PAIR OF MUTUALLY OPPOSITE HAMMERS, EACH OF WHICH CARRIES A PRE-SHAPING TOOL, A SECOND PAIR OF MUTUALLY OPPOSITE HAMMERS, EACH OF WHICH CARRIES A FINISHING DIE, SAID PAIRS OF HAMMERS BEING DISPOSED IN A COMMON PLANE AND SPACED FROM EACH OTHER BY AN ANGLE OF 90*, AND HAMMER DRIVE MEANS FOR DRIVING SAID PAIRS OF HAMMERS IN ALTERNATION TO PERFORM BLOWS AGAINST OPPOSITE SIDES OF BAR STOCK INTRODUCED BETWEEN SAID HAMMER DRIVE MEANS WHICH IS NORMAL TO SAID PLANE, SAID HAMMER DRIVE MEANS COMPRISING A COMPRESSED GAS SOURCE FOR DRIVING SAID SECONE PAIR OF HAMMERS. 